Cosmic rays acceleration at ultrarelativistic subshocks

We present the model of cosmic rays acceleration at ultrarelativistic subshocks and confront it with the observations of gamma-ray bursts and blazars. We investigate cosmic rays acceleration in shocks with Lorentz factors in the range 3 - 40. We show that fluctuations of the magnetic field downstream of the shock do not play an important role in the acceleration process. Results of numerical simulations for shocks with considered Lorentz factors and perpendicular magnetic field inclinations are presented. We fit the derived particle energy spectral index dependence on fluctuations of the magnetic field upstream and Lorentz factor of the shock with a function.